1. Field:
The field of the invention is evaporative air coolers, particularly such coolers which are relatively small but nevertheless efficiently cool large volumes of air, and are also capable of efficiently cooling warm air in the higher ranges of relative humidity.
2. State of the Art:
The principle of evaporative cooling of low humidity air has been exploited for several decades in the dryer regions of the United States and other countries. Present evaporative cooling devices typically comprise a low pressure, high volume air mover, such as a squirrel cage fan, mounted within a housing which incorporates sizeable highly porous evaporation pads arranged vertically in its walls. The loosely woven fibers of the pad are wetted to provide a large surface of water for cooling evaporation. The fan is adapted for delivery of air in high volume at low pressure, and the pads are accordingly thin in thickness and extensive in area. The incoming air is cooled inefficiently because it passes too quickly through the thin pads. That is, the full evaporative potential of the air is not utilized because the dwell time in contact with the wetted fibers is too short. Also, the air wafts quite gently through the pads with little of the mixing turbulent eddying which would accompany higher velocity and promote much more efficient evaporation. Low humidity air is required for significant cooling, so that these conventional units are of little value at the humidity levels found in many areas.
The required large pad areas result in impractically large coolers for many applications, such as automobiles, boat cabins and mobile trailers, where the interior space is limited and external mounting of the cooler is not desirable.
Clearly, there is a need for a more compact, more highly efficient evaporative cooler capable of cooling large volumes of air while itself occupying minimum space, and also capable of exploiting the full cooling potential of the air in both low and high humidity ranges.